HIV epidemic began with a single emergence of Simian Immunodeficiency Virus (SIV) some decades ago, and that virus gradually mutated and smoothly spread into human beings as Human Immunodeficiency Virus (HIV) worldwide. SIV is an animal virus originated in Africa in wild caught African green monkeys and chimpanzees.
According to Essex et al, HIV I or a virus very similar to it had moved to the cities of Africa even before mid of 1950s, either by introduction from the subhuman primates or migration of a few resistant carriers from a previously isolated tribes.
HIV would have been present for many generations in isolated tribal regions. A virus that could be a progenitor of HIV has been isolated from a chimpanzee in central Africa was also another evidence of HIV's origin.
How did the animal virus infected the humans?
First of all, HIV spread from the wild caught African green monkeys (Fig. 1.1) to the African people who killed the monkeys and smeared the blood on their bodies. They believed that it would definitely increase the libido. They might have thought that the blood of monkeys had an aphrodisiac effect.
Another superstitious belief was to kill these monkeys and smearing the blood on their bodies in view of attaining heaven since those monkeys destroyed their plantations.
During hunting, they had to run along with animals which might have produced aberrations to severe wounds while passing through the wild shrubs, plants and trees. Through those wounds, HIV might have gained entry into the African people.
How was it transmitted to the Whites?
Africa is a continent of natural wealth. Whites were in search of treasures. They worked in the mines for several months together. Those sex starved Whites might have had sex with the infected African people. Through them, HIV might have been transmitted to the Whites.
African people were utilized as slaves. Slave trading was first established in Africa. Slaves reached western countries through Congo (Zaire), Egypt and Haiti. Robust body of the African people might have attracted the Whites to have sex with them. It may be the reason for the spread of HIV among Westerners. Then the HIV had spread throughout the world by travellers.
In Haiti, HIV prevalence among pregnant women was 7.5 percent in urban areas and 5.5 percent in rural areas in 1993 itself, with the highest rate of seropositivity in the younger age groups (Bernard YM, Camara B, Ferrus A, et al. Resultants d'one etude de surveillance serosentinelle: Prevalence du VIH du VHB et de la syphilis chez les femmes enceintes dans 5 sites serosentinelles en Haiti. Haiti Epideniol 1994;1:30). Haiti is a 3 beautiful island which was considered as a holiday resort for Americans. Through them, HIV might have reached major cities of America.
How did they identify the transmission by blood?
Most of the HIV seropositives were haemophiliacs at that time. They received factor VIII, the anti-haemophilic factor (clotting factor) routinely and repeatedly to counter the clotting deficiency. The clotting factor is processed as a cryoprecipitate from the blood of multiple donors. If any donor of the cryoprecipitate had suffered from HIV, then the whole cryoprecipitate will be infectious. That's how the transmission of HIV through blood might have been established.
How did they identify the sexual transmission of HIV?
Haemophiliac's sexual behaviours had revealed that most of them were homosexuals, later it was identified in heterosexuals and established the sexual route of transmission.
FAMILY RETROVIRIDAE
Retroviridae makeup a large family of virus infecting mainly vertebrates. They have a unique replication cycle whereby their genetic information is encoded by RNA which is transcribed into DNA in the host cell. Retrovirus can rapidly alter their own genome by recombination and mutations under selective environmental stimuli.
Subfamilies
Oncovirinae (Tumor Producing Virus)
They usually convert the normal cells into tumor cells, hence the name transforming virus. Now it is popularly called as Adult T cell lymphoma / lukaemia virus (ATLL), e.g. Human T cell lymphotropic virus I and II.
Lenti Virinae (Lenti means slow)
Spuma Virinae (Foamy virus)
No reportable disease even though it exists in humans.
COMPOSITION
HIV is composed of three basic components (Fig. 1.2)
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The Envelope
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RNA Genome
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Structural Proteins
Virus are composed of a nucleoprotein core surrounded by a lipid bilayer. The nucleoprotein core comprises two copies of the viral genomic RNA.